Gasification of coal



Feb. 2 1926.

K. P. M ELROY GASIFICATION OF COAL Filed May 10, 1920 gnuenfoz Patented Feb. 2, 1926.

1,571,877., UNITED STATES "PATENT OFFICE.

KARL P. MGELBOY, OF WASHINGTON, DISTRICT OIE COLUMBIA, ASSIGNOB '10 FERRO CHEMICALS me, or DELAWARE.

WASHINGTON, DISTRICT OF COLUMBIA, A CORPORATION OF GASIFICA'IION GOAL.

To all whom; it may concern;

Be it known that-I, KARL P. Mc ELnoY, a citizen of the United States, residing at \Vashington, in the District of Columbia, 5 have invented 'certainnew and useful Improvements in the Gasification of Goal, of

Which the following is a specification.

This invention relates to the gasification I of coal; and it comprises a method of utiliz- 1 ing bituminous coal and like fuels for the production of gas and by-products wherein the fuel is first methodically heated and distilled in the presence of a current of hot gases, thereby producing gas and oily prodacts as well as an open textured residual car bon, and this carbon is then gasified by hot air under conditions giving a hot gas of high fuel value, a portion of this gas being used to furnish heat for the distilling operation and another portionto furnish heat .tothe air used; all as more fully hereinafter set forth and as claimed.

Under carefully regulated distillation conditions various oil shales'may' be used as a source of oils of the petroleum type, that is oils of thecharacter known as paraifino-id ;v and the same kind o-fproducts m-aybe obtained from various bituminous fuels, such as bituminous coal, cannel coal, lignites or brown coals, asphalticcoals and pitches, peat, and the like, if distillation be conducted at carefully regulated temperatures and in the presence of a current of steam or gas to sweep away the volatiles as fast as formed. \Vith quick or forced heating of the fuel or any superheating of the produced vapors, these fuels also furnish oils but in less quantity and of quite another character, that of theoils of ordinary coal tar. For various reasons, however, it is difficult to utilize these bituminous fuelsfor oil making. at a profit by the processes heretofore proposed. It is an object of the present invention to provide a. method by which this may be done; production of oily products suitable for motor fuel, illumination, lubrication, andthe like,

being made an incident to, and a preparatory stage m, a high speed gaslfication of.

residual carbon. Theftwo ope-rations how 5 separate and are independently regiil atcd.v

Vvhile other and more complicated types 'gasification in the base.

ever although conducted as successive stages of apparatus may be employed, a simple shaft furnace suffices, distillationbeing performed in the upper part of the shaft and In order to, give independence in operation however a plurality of gas outlets are used, onefbeing located in the gasification zone so that any adjusted fraction of the hot gas therein pro-- duced can be separately withdrawn without ascending through the descending body 'of coal. By so doing, conditions in the distil lation zone, which is advantageously maintained a substantial distance above the gasitication zone, are made readily controllable and independent of gasification conditions.

Most of the distillation of coal takes place between 300 and 400 0. although it begins around 250 and continues more or less up to 500, or'thereabouts. Under the action of the heat there is a breaking down or dissociation of the coal, or of its constituents,

v with evolution of various hydrocarbon gases and vapors; these primary products in turn.

tending to break down or crack with formation of secondary products. In order therefore to obtain any large yield of primary products by distilling coal a careful adjustment of thermal and other conditions must be made. The temperature of the coal should be caused to rise progressively and gradually through the ranges mentioned, and particularly the300-400 degree range: opportunity being given for the escape of the volatiles formed at onev temperature stage before going ao the next stage. Volatilesshould be removed from the point. of

formation as quickly as possible and without exposure to higher temperatures than those at which they are formed. Any quick or abrupt heating of the coal disturbs the regularity of the distillation and loads to losses. With a descending column of coal traversed by a countercurrent of hot gases to act as a heating agent and as a carrier agent for sweeping forward vapors, these requirements can be met; it being possible to establish and maintain in such a column a comparatively long. distilling zone with a gradual temperature gradient between the stated limits. In so doing the'length and temperature gradient of the distilling zone are controlled by correlating the flow of hot gases into the bottom of the zone with aremoval of a controlled amount of vaporgases are allowed to flow laden gases at the top of the zone. Much or mom of the hot gases are diverted out of contact with the coal. Merely enough hot u ward through the coal beyond the point of diversion to give the desired. amount of preheating to downcoming fuel. Vapor-laden gases may be diverted in con'trolledamounts at aplurality of points, thereby establishing and maintaining a corresponding plurality of zones of I adjusted temperature.

and vapors are sent to condensing means.

The temperature at which the vapor-laden gases are removed is of great importance, not only as'regards the character of the products formed but as regards the working of the apparatus. In largefpart the primary volatiles consist of vapo-rs'of high boiling oils and waxes; these vapors-existing as such at about-300 C. If removal be at, say 250 because of the high temperature and of the dilution with gases. Withany lowering of temperature, such as is caused by contact with colder coal, oily and waxy bodiescondense in the coal and travel downward. with it, returning to thedistillation zonewhere they are revaporized and cracked. In s.ecuring maximum yields of these highboiling hydrocarbons it is therefore in general desirable to remove the gases and vapors (3., a larger yield of light oils is secured at the-"expense of the heavier oils condensed in the coal and ultimately cracked down.

In what ll regard as the best embodiment 555, of my invention 1 divert. the main body of the vapor-laden gases at a temperature of about 300 6., sending the diverted, materials to suitable condensers. and scrubbers.

The rest of the gases ascend upward, preheating the descending .c'oal an-ddepositing therein oils condensing from the gas at temperatures below 300; Thesecondensed oils pass downward andultimately (save to. the

extent they may be lcra cked' down) rejointhe major flow.1'A certain amount ofdistillation takes place above the-300 outlet.

. So far as this produces con-densable' hydrocarbons they go downward; so far as it producesgases and'lightoil vapors they go upward. l find it desirable; and particular ly with moist coals to-jmake' the'linal di'ver-.

sion of the gas current at a temperature around 100 C. There may however advantageously in some cases be an intermediate diversion at say 250. v y

With a. diversion 9.5300? and another at 100, the products recovered fromthe former contain large amounts of high boil:

ing' oils and waxes (lubricating oils and paraflin) as well as intermediate'oils of the nature of keromne and light oils, such as gasoline. With some coalsthere may also be various aromatic hydrocarbons, such as benzol; with others aromatics are not formed. The products diverted at 100 (3.,

The diverted gaseS' arisa? on cooling usually give water and gasoline;

a further portion of gasoline being recoverable by compressing or scrubbing the resid ual gases. These gases are rich in heavy gaseous hydrocarbons.

If the primary diversion be at250 C. in

lieu of 300, the proportion of gasoline and light oils increased at the expense ofheavy oils and waxes. Where recovery of very heavy hydrocarbons is desired, there may, be a diversion at 400 in addition to, or 111- steadof, the diversion at 300.

The coal pasing downward beyond the" distilling zone is usually of a loose open or porous texture quite different from that of ordinary coke. Coke is usually produced 1 under conditions adaptedto make it as dense as possible ;.these conditions including a high temperature which causes distilled volatiles to undergo a secondary decomposition with deposition of carbon in the coke pores. In

the present invention it is the purpose to avoidthissecondary decomposition,,vapor- I V cluce somewhat more gas at the expense of 5 the heat disappearing. Low temperature Y operation ,is however slow, so that a given apparatus'does not turn out much'gas per hour; and, furthermore, the gas is ofrelas tively poor quality, containing considerable proportions of carbon dioxid. At all tem eratures-below' about 1000 0., gas pro- 'guced b blowing carbon withairmust, be-

cause 0 certainequilibrum relations, have i a relatively large ratio 'of GO t0 GO.

The-gasification in the-base of the descending column of-fuel may be doneunder ordinarygas producer conditions with the production-,frornfired carbon of the ordinary type of producer-gas; theonly difi'er- 'ences thenbe'ing that a portion of gas is taken off directly'irom' the hotzone and that. gasification, because of the peculiar or sintered ash, andanother being to pro- I type of carbon, is more rapid. But I find it much better to operate at a much higher range of temperature; one suficient to slag the ash constituents of the fuel, a little lime or limestone being added to the charge to aid I in this. Ordinary lime-alumina-silica slags require a temperature of 1300to 1400 C. At thls'high temperature gasification of carbon blown with hot air is ,very much more rapid; a comparatively small apparatus giv ng as much gas as a battery of producers run in the usual way. In addition to getting .hlgh

lowermost gasification zone is that of a prof ducer operating at hi hspeed because of the open textured car on supplied 1t and because of the high temperature, a temperature suflicient to form a freely liquid slag,v

and giving a gas of the composition normal" at temperatures above 1000 C., with about 7 33 per cent CO; all the oxygen of the air blast being converted into CO without persistence of CO any; formed reacting with car on to form 200. Since. however the artial'oxidation or semicombustion of car on to CO" by a hot air blast gives much more heat than is requisite to keep the fuel mass at the 'slagging.

temperature there is a tendency, in the absence of anything-to'take up the surplus heat or constitute a load, for'the. temperature to rise above this point; and this is'not desirable for various reasons, one being difficulties with furnace linings. Therefore I advantageously use a substance reacting endothermically to control the temperature and prevent such a rise, thereby obtaining gas at theexpense of the As the endothermic reagent absorbing the heat units in excess of the amount necessary to keep the producer zone at the necessary slagging temperature, I can use steam; a little steam or water vapor being admixed with the inflow of hot air. This gives me a sharp temperature control in the producer zone and somewhatmore gas at the expense. of t e heat. In so doing, however, the gases abstracted from the producer zone are still at the inconveniently high .temperature of 1400 C. or thereabouts audit is desirable to cool them somewhat, say, to about 1000 C. before using the ordinary heat exchanging devices. As stated I desire to use sensible heat from the gas in heating my air blast.

' 'As the endothermic substance in the hot The Withdrawn hot gas is apt to carry .CO primarily terchangermore or less solid matter (dust) in addit1on to such fumes of cyanid as'may be prescut, and for this reason and also because of its high heat, it isdesirable to purify and a it cool it somewhat prior to handling it in the usual heat exchanging devices (checker work or recuperators). Both purposes may be accomplishedby passing it through a bed of charcoal or coke containing more or'less.

soda which'cools the gasby the formation of cyanidand also'enriches the gas to a concomitant extent by the production of' more CO and withdrawal of nitrogen; Any

cyanid fumes or vapor carried by the gas coming from the producer are WltlltllitVVlIlIY the carbon, being adsorbed thereby. Vapors of cyanid at 1400 or thereabouts carry a large'quantity of sensible heat and of latent heat of, vaporization; and this "heatis also utilized for formation of cyanid in the filter in addition to the sensible heat of the gas ing dust and the like'aud delivers a clean hot gas of reduced temperature, suitable for direct use in any ordinary type of heat in- The carbon filters may be steamed out from time to time 'to convert the nitrogen 'of' the'contained cyanid into ammonia and reproduce alkali.

The ammonia formed in steaming can be collected in any of the usual ways and by any of the usual apparatus. The alkali remains in the carbon and the carbon may be used againas a filter and cooling or heat absorbing material until the proportion of carbon becomes too small. When it is thus .itself. The carbon filter also removes fly- L impoverished, it may be charged into the producer.

Working in the described manner, a cooled clean producer gas free from tar may be changer, carrying about 40 per cent or 'mo're obtained from the'filter and heat interof CO, instead of the theoretical 33 per cent.

It is suitable forengines, furnace firing, and the like. The richness of the distillation gas coming from the upper zones varies with the fuel and the circumstances, but after' poses.

In the accompanying illustration I have shown, more or less diagrammatically,-certam organizations of apparatus elements within my invention and adapted for use in the described process.

In this showing,.which is a cal section, certain parts being shown in elevation, element 1 is a shaftfurnace or gas producer of masonry or other suitable material. Its walls may be watercooled where necessary. .At its top it carries a hop view in verti-' per feed 2 through which may be supplied the coal which is to be'distilled and gasified.

This coal is most advantageously one rich of the heat in the crucible or hearth is to be utilized by sodium carbonate as an endothermic agent, ordinary soda ash in the. cor

' rect amount may be fed in with the coal, or

' connections not shown.

recovered alkali from-a later operation may be so supplied.

As shown the shaft has a bosh region 3, similar tothat. in a blast furnace, air bustle pipe 4 and tuyeres 5. It is also provided with slag outlet 6. Leading'from thev bosh region are outlet pipes 7 for hot gas. A

continuous annular outlet may be provided.

These elements are advantageously water cooled. They lead to hot gas chamber 8 which communicates through pipe 9 with carbon filter 10, containing charcoal or coke; and soda or other alkali and adapted to 'col'-;

lect cyanid condensed or absorbed from passing gases together with liquid cyanid formed from the soda and carbon by reaction with the nitrogen of the gas. In practice several of these filters maybe used. in alteration,

but only one *is shown, The, filter has load-' ing inlets 11 at the top and discharging manhole 12 at the bottom. It may' be pro vided with steam connections and ammonia As. shown, it is of U-shape, as this structure is advantageous for collecting molten cyanid draining down. Passing through the 'filter, the gas, now cleaned and somewhat ,cooled by the endothermic action of cyanid formation, passes through exit 13 to heat exchanger 14, shown diagrammatically. It may be a recuperator of aregenerator of any of the usual types. Air passes intothe heat exchanger from fan 15 and goes thence-through hot air conduit 16 to the air bustle pipe. Gas leaves wthe 'recupe'rator through pipe .17 to a suitable place of use. The ratio of air going through 16 to the-gas leaving through 17 can be adjusted as maybe desired. All the gas formed in the crucible or gasifying zone of the producer which-is not Withdrawn as described through outlets passes up through the downcoming fuel in the shaft, heating "and carbonizingit-and freeing it of volatiles in the manner described. Passing upward through the mass it mixes with and carries forward the distillation gas formed and the vapors produced. If desired, a little steam or atomized water mayfuel in the distillation zone and are in part Various potasof amajor proportion of the discharged at 19 into a' collecting bustle, pipe 20, the discharge being at any temperature desired; usually between 250 and 300- C. As shown, from this bustle pipe gases and vapors pass through conduit 21' into tar trap and air cooled chamber 23, provided with liquid outlet 24 and gas outlet 25. The gas and vapors,,somewhat cooled, next pass through water cooled condenser 26 provided withtrap 27, having a liquid outlet 28 and a gas outlet 29. Condensed hydrocarbons and ammonia liquor are re m0ved through 28. Uncondensed gases next volatile gasoline, benzol, and the like. The

scrubbed gas passed .out' through outlet con- 'duit 33 and thence by pipe 34 to a'suitable place of use. Or it may be led down by pipe 35 to. be admixed with gas from the 'gasifying zone.

Y Returning to the shaft, a minor flow-of hot gases is allowed to pass upward, beyond through the fuel'to preheat and dry it, this minor flow being diverted from contact with the c0al,'usually, at a'temperature around.

100 ,C. 'The diverted gas passes into collecting bustle pipe 36 and thence into air cooled chamber 37 provided with liquid out let 38 and gas outlet 39. From the liquid bu discharges, in addition coils is collectedin trap 41 and discharged 1'35.

at 42. 'Uncondensed as is sent to the scrub-- the point of diversion'of the major flow,

bing device previous y described by means of conduit 43. Draft conditions throughout the system are adjusted by means of suitable suction and pressure fans. Suctionifa'n 45 on the hot gas line .7 to 17 from the' producer; fan 46 on the line 19. to 34 carrying the major flow offvap'or laden gases and fan 47 on the minor vapor flow line 36 to 43 can be so operated in conjunction as to establish any desired ratio of flowinthese three lines. The outlets 36, 19 and 7 mark the division of the producer roughly into three more or less-overlapping zones of preheating, distilling and gasifying.

shown, the relative sizes ofbustle pipes 8 and 20 permit of the withdrawal through 8 in the gasifying zone. 7

Instead of using charcoalor other form of carbonin the filter 10 for the hot as from the gasifyin zone, any'other suita 1e absorbing materia may be used capable of i I gases formed withstanding the action of alkali; such as burnt dolomite. In lieu of using scrubbing oil for removing gasoline and vapors of volatile hydrocarbons, ordinary types of absorbent fifters containing charcoal, silica vapors are withdrawn from-the coal at a relatively high temperature-and where the amount of carrier gas is not very great, the condensed high boiling OllS and waxes'may then scrub .the gas sufficiently themselves abstracting a suificient amount of gasoline .and benzol. But ordinarily it is an eco-.

nomical procedure to scrub the absorbed residual gasoline out of the vapors by a special treatment.

Slagging temperatures and the high speed v gasification incident thereto may be maintained in the gasifying zone without the useof hot air. In this event the heat eX-- changer shown and described need not be used. With cold air blast there is usually not much margin of heat" available for the formation of cyanid vapors in the hearth, butsome cyanid can form and in any event the sensible heat of the gas will produce cyanids .in the carbon filter in the manner described. It is therefore advantageous, even in using air at the ordinary temperature to employ the carbon-alkali filter. The gases discharged at 800-1000 C. are still as hot as is desirable for furnace firing and other uses for hot gas. I In using cold air blast it is desirable to have the hot gas outlet from the producer at a rather higherlevel in the boshes than when hot air blast is used; or to use an auxiliary outlet t-aking out some gas at 400 to 500 C. in addition to the diversion outlets already described. As regards the actions in the hearth it is of course the same Whether heat units are returned to the hearth in air or in carbonized residue. WVhen hot air is used it may of course be heated in a stove or any other suitable device But for the present purposes I regard the useof hotair heated by sensible heat of the gas delivered from the gasifying zone as to be ,on the whole the most advantageous. v

In using a hot air blast and supplying a-lkalies with the coal, the supply of alkali is so correlated with the temperature of the blast and with the heat taken away from the hearth zone in hot gases as to prevent the hearth temperature rising much above the desired 13001400that is, above the point at which slag will still form and run freely, observed tendencies to a rise of temperature being corrected by an increase in the proportion of alkali supplied with the fuel and to a drop in temperature by a; diminution in the proportion of alkali sup-' plied.

The oils and waxes collected in the various condensers are distilled and otherwise ed in the u al c mm c al Ways, o ob- ,products.

min the usual commercial products, gasoline, kerosene, lubricating oils, waxes, and the like. Sometimes phenols, cresols and the like, accompanythe distillate; this being particularly the case with coals yielding benzol, toluol, and the like, as primary They may be extracted and recovered in the ways usual with coal tar oils. In a general Way however the refining methods used withpetroleum oils are better adapted to the present oils than are those used with coal tar oils. Such ammonia as accompanies the distillation gases may be recovered by the usual methods and apparatus, not shown.

What I claim is 1. The process of utilizing bituminous coal and the like fuels which comprises establishing and maintainin a ddscending column of such fuel containing alkali, blasting the base of the column with hot air at a suificient temperature to maintain slag-forming temperatures in such base, diverting from such" base a regulated portion of the hot gas formed, collecting cyanids therein contained, exchanging its heat with air to produce such hot air, allowing the rest, of the gas to aswith a regulated quantity of hot producer gas while withdrawing distillation products in vapor form from said column at points of adjusted temperatures, then ga ifying the carbonized base. of said colu n with hot air to make freely running slag and to generate said hot producer gas, while removing from saidbase at substantially the fuel temperature thereof such proportion of said producer gas as is not needed for,said distillation. y

3. The process of utilizing coal which comprises first drying and preheating the coal by gases having an initial temperature .of about 300? 0. passed through said coal and removed at a temperature of about .100 (l, distilling and carbonizing the dried coal by an adjusted quantity of hot gases passed therethrough and removed from contact therewith at a temperature of about 300- C., said removed gases containing condensible hydrocarbons, and finally gasifying the residualcarbon at a temperature in excess of 1000 C. by means of an air blast to produce hot rich gas of which said adjusted quantit only is used in said carbonizing and distllling.

4. In the peration of updraft gas prc= duoers on bituminous coal, the process which comprises establishing and maintaining slagmelting temperatures in the base with the aid of preheated air, diverting a portion of the gases thereby produced, transferring heat from said gases to air to furnish said preheated air, passing an adjusted portion of said gases through heated coal to cirbonize the same and furnish distillation products, diverting a portion of said gases, together with distillation products, from said coal when their temperature has fallen to about 300 C, and passing the .undiverted portionof said residual gases through fresh coal to heat and dry the same 5. In the operation of a gas producer establishing and maintaining 'a vertical 001- umn of distilling bituminous coal with a carbonized base, gasifying the said carboi1- ized base at slag-melting temperatures with the aid of heated air, passing upward through said column such portion of the hot gases thereby produced as will flow freely therethrough while diverting the rest of the hot gases, diverting a portion of the upward --passing gases; when their temperature has fallen to a point in the neighborhood of 300 0., and passing the rest of the hot gases to contact with the coal above the latter point of diversion to heat and dry the coal.

6; In the utilization of bituminous fuel, the process which comprises establishing and maintaining a descending column of such fuel, asifying the base of said column by an air blast to produce hot gas, diverting a controlled amount of said hot gas from contact with the fuel while permittingthe rest to ascend through the column, di-

verting a portion of said ascending gas from contact with the fuel at atemperature in the neighborhood of 300 0., and diverting the residue of said gas from contact with the fuel at a lower temperature.

7. In theutilization of bituminous fuel,

\ the'process which comprises establishing and maintaining a descending column of such fuel, gasifying the base of said column by an air blast to produce hot gas, diverting a controlled amount of said hot gas from contact with the fuel while permitting the rest to ascend through the column, diverting a portion of said ascending gas from contact with the fuel at a temperature in the neighborhood of 300 C. and diverting theresidue of said gas from contact at, a temperature of about 100 C. v

8. In the utilization of bituminous fuel,

the process which comprises establishing and maintaining a descending "column of such fuel with a carbonized base, gasifying said carbonized base with air to make clean producer gas, removing from said base the greater part of said gas so made while causing the rest of said gas to ascend in counter flow to said fuel to establish and maintain nearer? tions and removing adjusted portions of the ascending gas together with vapors carried thereby at different-points along the height of said column-to establish and maintain said distilling zones of adjusted differential' temperatures.

9 In the utilization of bituminous fuel, the process which comprises establishing and maintaining a descending column of such fuel with a carbonized base, gasifyin the said base with air to make clean pro ucer gas, removing the greater part of the producer gas so formedwhile permitting the rest to ascend through said column to establish and maintain distillation conditions therein, removing a portion of the ascending gas, together with volatiles carried thereby, after a period of travel in contact with the fuel and before its temperature has fallen below a temperature range of 250 to 300 (3:, and permitting the rest of the gas to ascend through the coal above the point of removal. 7

10-. In the utilization of bituminous fuel,

,the process which comprises establishing and maintaining a descending column of such fuel, gasifying its base with hot air under conditions affording temperatures suflicient to form freely running slag with ash constituents of such fuel, removing a controlled fraction of the hot gas thereby produced while permitting the rest to ascend through the. fuel column, abstractin heat from the removed portion and transferring it to air for use in gasification, removing a controlled fraction of the ascending gases after a period of travel in contact with down coming fuel, said fraction being removed at a temperature suflicient to permit it to carry vapors of high boiling oils and removing theremaining fraction of the ascending gas after a further period of travel in contact with downcoming" fuel.

11. In the utilization of bituminous fuel, the process which comprises distilling such fuel by a current'of hot gases passing therethrough and removed at a temperature sufficient to permit them to carry forward vapors of high boiling oils and waxes, gasifying the residual open textured carbon by hot air underconditionsaffording slag melting temperatures, using-a regulated propor tion of the hot gas produced to furnish such current, removing the remaining proportion of such gas, cooling the removed hot gas somewhat by the aid of an endothermic chemical reaction, and further ,cooling said gas by air to aid in supplying said hot air.

12. In the utilization of bituminous fuel, the process which comprises distilling such fuel to remove primary volatiles, gasifying the residual hot open texture selbon by hot terially above such slag-running temperatures, removing hot gases at this temperature, further cooling the removed gas with the aid of an endothermic chemical reaction, and completing the cooling of the gas by air used to furnish said hot air.

13. In the utilization of bituminous fuel, the process which comprises admixing said fuel with slag forming fluxes and alkalies, distilling the fuel under regulatedconditions to form and remove a large amount of distillation products and leave an open textured hot residual carbon, gasifying said residual carbon by a hot ailblast at slagforming temperature-s'to form a hot rich gas carrying cyanids, filtering and cooling said,

gas through a carbon filter containin g alkali, and abstractingiresidual heat from the filtered gas, the abstracted heat beingdelivered to the air for the blast. i

14. In the continuous operation with hot air of slagging gas producers provided with outlet for gas from the slugging zone and charged with fuel, fluxes and an alkali compoundto serve as a as forming endothermic reagent in the gasi cation' zone, the process of controlling the temperature of the slagging zone which comprises so correlating the proportion of alkali compounds charged in the fuel with the temperature of the hot air as to maintain a temperature in said zone merely sufficient to deliver the slag in molten, freely running form, increasing-the proportion of alkali with rise of the air temperature and decreasing alkali with fall of said temperature.

15. In the gasification of coal, the process which comprises establishing and maintaining a vertical column of distilling bituminous fuel with a carbonized base, blasting said base with hot air at a temperature at least sufiicient to fuse. ,and run ash components as slag, withdrawing a regulated bon, and transferring the heat of the filtered gases to air in furnishing sald hot air.

portion of the hot gases from said base, filtering the withdrawn hot gases through car- 16. In the operation of an updraft gas producer blown with air and supplied with bituminous coal as a layer of substantial depth overlying the combustion zone, the

' process of increasing the speed of operation and regulating and enhancing draft through such layer which comprises removing a portion of the'gas produced in such combustion "zone directly from the combustion zone. and

removing another portion "after passing through such layer with such adjustment ofthe ratio between the two portions of gas so removed as to maintain the fuel layer open and pervious and to deliver to the .an updraft gas producer operated with air of a moving body of bituminous fuel by a countercurrent of a limited quantity of hot gases passed therethrough, the process of controlling the composition of distillates obtained in successive zones thereof which comprises removing successive definite frac 7 tions of such gases together with distillates carried thereby at different points along their line "of travel, and balancing the amount of gases passing through each such zone against the amount of gases and'distillates so removed and these amounts against each other so as to establish and maintain definite temperature gradients in said successive zones. 7

18. In the high-speedcomplete gasification of bituminous coal the process which comprises gasifying such coal, by a hot air blast, gasification being at a sufficient temperature to form free running slag, remov-. ing apart of the hot gas directly from the gasifieation zone and transferring a portion of its heat to the air to produce said hot air blast while, causing an adjusted portion of *the 'hot gas to flow' in countercurrent contact with incoming coal to heat and distill said coal and to convert it into an open textured rapidly gasifying carbonized carbon which reacts with said hot air blast.

19. In the utilization of bituminous coal, the process which comprises establishing and maintaining a descending column of such coal in a suitable shaft furnace operated as a gas producer maintaining a temperature in the base sufiicient to 'form a while still at a temperature sufficient to ,carry substantial amounts of vapors of highboiling hydrocarbons, and removing at a higher point the rest/of the ascending gases together with substantial amounts of vapors of low-boiling primary distillation products. 20. In the operation of an updraft gas producer with air, the process of improving productive capacity which comprises establishing a column of descending fuel undergoing low temperature distillation with a carbonized baseand a substantially separate zone in which the carbon of said base is completely gasified, preheating and distilling said fuel by ascending c ounterflow of an adjusted quantity of the products of said gasification, while diverting directly from said zone of gasification such proportionof said gasification products as is not needed for said preheating, distillation and carbonizing, said proportion being a major part of said gasification products 21. Inthe operation of an updraft gas producer with air, the process which com p prises establishing and maintaining a sub- QT gasproducer blown with am, the process which comprises establishing and maintainstantially separate zone of. gasification' of carbon and preheating said carbon by an adjusted quantity of the products of said gasification, While divertin a major pro portion of said products directy from the zone of gasification and transferring the heat of diverted gases to the-air used in said carbon gasification. 22. In the utilization of bituminous fuel with the aid of updraft gas producers using endothermics and preheated air, the process which comprises establishing and maintain-- ing a vertical column of distilling fuel-With a carbonized base, said base including a separate zone of carbon gasification, pre-' heating said carbon and supplying heat for carbonization by an adjusted flow ofthe products of saidgasification in countercurrent to descendingfuel, while diverting a erner? substantial proportion of said products from said gasification zone and transferring the gases to the air used ing a descending verticalcolumn of fuel with a tar free carbonized base and the upper portions of said column undergoing low temperature carbonization by aid of heat carried in an adjusted quantity of gases produced in the complete gasification of the carbon of said carbonized base with air,

while removing the remainder of said gases without contact with nor transfer of heat to a the fuel undergoing carbonization, said remainder being a clean tar free producer gas, and said remainder constituting a major proportion of the gases produced from said air; c a

In testimony whereof, l afix my signature hereto.

K. P. MGELROY. 

